A method of the kind mentioned in the opening paragraph is known from EP 1 104 799 A1. It is described how in this way e.g. Eu2+-doped M2Si5N8 (M=Ca, Sr, Ba) is manufactured that strongly absorbs UV-blue radiation and converts this absorbed radiation efficiently into red light.
A drawback of the known method is that the conversion efficiency of the phosphors obtained by said method is not satisfying. Moreover, the conversion efficiency drops due to degradation of the phosphor.